Fix build with rust-1.81.
https://bugs.gentoo.org/942191
https://github.com/coastalwhite/lemurs/commit/09003a830400250ec7745939399fc942c505e6c6
--- a/src/config.rs
+++ b/src/config.rs
@@ -645,7 +645,7 @@ struct Variable<'a> {
 }
 
 impl<'a> Variable<'a> {
-    const START_SYMBOL: &str = "$";
+    const START_SYMBOL: &'static str = "$";
 
     fn span(&self) -> std::ops::Range<usize> {
         self.start..self.start + Self::START_SYMBOL.len() + self.ident.len()